Clock

Clock service contains some functionality related to time and scheduling.

To get the current time in a specific time unit, the currentTime function takes a unit as TimeUnit and returns UIO[Long]:

val inMiliseconds: URIO[Clock, Long] = currentTime(TimeUnit.MILLISECONDS)
val inDays: URIO[Clock, Long] = currentTime(TimeUnit.DAYS)

To get current data time in the current timezone the currentDateTime function returns a ZIO effect containing OffsetDateTime.

Also, the Clock service has a very useful functionality for sleeping and creating a delay between jobs. The sleep takes a Duration and sleep for the specified duration. It is analogous to java.lang.Thread.sleep function, but it doesn't block any underlying thread. It's completely non-blocking.

In following example we are going to print the current time periodically by placing a one secondsleep between each print call:

def printTimeForever: ZIO[Console with Clock, Throwable, Nothing] =
  currentDateTime.flatMap(time => putStrLn(time.toString)) *>
    sleep(1.seconds) *> printTimeForever

For scheduling purposes like retry and repeats, ZIO has a great data type called Schedule.